current pkgsrc, thunderbird failure

Hi,
now that I updated distribution to current, I'm working my way upwards
on the packages again.
Thunderbird fails to build:
checking for gconf-2.0 >= 1.2.1 gobject-2.0 ... checking __attribute__
((aligned ())) support... trying 64
64
checking for vpx >= 1.0.0... Package vpx was not found in the pkg-config
search path. Perhaps you should add the directory containing `vpx.pc' to
the PKG_CONFIG_PATH environment variable No package 'vpx' found
configure: error: Library requirements (vpx >= 1.0.0) not met; consider
adjusting the PKG_CONFIG_PATH environment variable if your libraries are
in a nonstandard prefix so pkg-config can find them.
configure: error: ./configure failed for mozilla
*** Error code 1
But I have vpx installed (and rebuilt against current stuff too):
$ pkg_info | grep vpx
libvpx-1.2.0 On2 VP8 library from Google
It appears that it is pkg-config that it is not finding it :( Do I need
to "make replace" package config? or even set up something manually?
That shouldn't be necessary.
Riccardo